Alkalis In. Colorado 
49 
sulfate is easily explained. If the two salts be brought together in solu¬ 
tion they simply exchange the acids, forming a more difficulty soluble 
salt and an easily soluble one, the sodic carbonate becomes sodic sulfate 
and calcic sulfate becomes calcic carbonate. Another change which 
may take place is the result of the action of salt, sodic chlorid, on calcic 
sulfate, in which the sodic chlorid becomes sodic sulfate and the calcic 
sulfate becomes calcic chlorid becomes sodic sulfate and the calcic sul¬ 
fate becomes calcic chlorid. There are many other changes of this sort 
that are possible and which undoubtedly take place in certain localities. 
It seems that we are compelled to apply this principle of exchange 
which we are quite sure takes place in some instances to other cases 
in which we are not so certain that the conditions are the same. We 
can feel quite satisfied that calcic chlorid has been formed from calcic 
sulfate and sodic chlorid if both of these salts are abundantly present in 
the soil, but if one of them is present in small quantities only, and we 
still find the calcic chlorid present, especially in spots, and that some¬ 
times in improbable looking places, this explanation may fail to be en¬ 
tirely <^atisfactory. We find some such cases in Colorado. We find some 
magnesic sulfate and occasionally chlorid in some alkalis and I may say 
always in the ground- and many spring-waters. The fact that these 
magnesic salts are very easily soluble accounts for their presence in the 
waters and their formation may take place in a manner similar to the 
formation of calcic salts. If magnesic carbonate and sodic chlorid act 
upon one another, both products, sodic carbonate and magnesic chlorid, 
are soluble. Magnesic sulfate may be formed in a similar manner, and 
if magnesic sulfate and calcic chlorid chance to mingle, there will be a 
change resulting in the formation of calcic sulfate and magnesic 
chlorid. The magnesic salt occurring most frequently in our waters 
and alkalis is the sulfate. These salts sometimes make up as much as 
35 percent of our ordinary alkali and occasionally they are even more 
abundant than this. 
These sulfates, which constitute the so-called “white alkalis,” while 
poisonous to plants, some of them in comparatively small quantities, are 
so modified in their action, when in the soil and mixed with one another 
that extremely large quantities fail to produce seriously injurious re¬ 
sults. The calcic sulfate in some instances, as I have elsewhere men¬ 
tioned, may, when very abundant, produce a yellowing of the leaves on 
apple trees, and lime salts may be the primary cause for the bleeding 
described in a previous paragraph, but ordinarily we do not obseve any 
ill effect from the presence of very large quantities of these salts in the 
soil. The poisonous action of the magnesic salts is so greatly reduced 
by the presence of other salts in the soil that in all ordinary cases we 
may neglect it altogether. I have cited four cases in illustration of the 
fact that the amount of alkalis which may be present in the surface 
